Conventionally, known is a vehicle steering apparatus comprising a first shaft connected to an operating member; a second shaft connected to vehicle wheels so as to change the setting angle according to the rotation thereof; a rotation transmission mechanism having rotation transmission elements which connect the first shaft with the second shaft so as to enable the rotation to be transmitted and enable the rotation transmission ratio to be changed based on the change of the rotation speed; and an actuator for changing the rotation transmission ratio by changing the rotation speed of the rotation transmission elements (c.f. specification of German Patent Application Publication No. 10214655).
This rotation transmission mechanism has a first sun gear, a second sun gear disposed coaxially and facing with the first sun gear, a first planetary gear which engages with the first sun gear and has an axis parallel with the first sun gear, a second planetary gear which engages with the second sun gear and rotates together with the first planetary gear coaxially, and a carrier for rotatably supporting both sun gears and both planetary gears around their respective axes as the rotation transmission elements.
The rotation transmission ratio between the first shaft and second shaft is changed by changing the rotation speed of the carrier by means of the actuator, with connecting the first shaft to the first sun gear and connecting the second shaft to the second sun gear. The ratio between the amount of operation of the operating member and the steering angle of the vehicle wheel can be changed by changing the rotation transmission ratio between the first shaft and second shaft.